JP6939777B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire, and more specifically, by making a notch in the outer peripheral surface of the band-shaped sound absorbing material adhered to the inner surface of the tire, the outer diameter growth of the tire at the time of inflating the tire is followed, and the band-shaped sound absorbing material is formed. The present invention relates to a pneumatic tire capable of relaxing the generated tension, improving the durability of the band-shaped sound absorbing material, promoting heat dissipation from the band-shaped sound absorbing material, and improving high-speed durability.

One of the causes of tire noise is cavity resonance due to vibration of air filled in the tire cavity. This cavity resonance sound is generated when the tread portion of the tire that comes into contact with the road surface vibrates due to the unevenness of the road surface when the vehicle is running, and this vibration vibrates the air in the tire cavity portion. There is a frequency range that becomes noise in this cavity resonance sound, and it is important to reduce the noise level in that frequency range in order to reduce tire noise.

As a method for reducing noise due to such a cavity resonance phenomenon, it has been proposed to attach a sound absorbing material made of a porous material such as sponge to the inner peripheral surface of the tread portion by an elastic fixing band (for example). See Patent Document 1). However, when the sound absorbing material is fixed by the elastic fixing band, there is a problem that the elastic fixing band is deformed at high speed.

On the other hand, a method of directly adhering and fixing the band-shaped sound absorbing material to the inner surface of the tire has been proposed (see, for example, Patent Document 2). However, in this case, since the band-shaped sound absorbing material is directly attached to the inner surface of the tire, heat storage occurs in the tread portion, and there is a problem that the high-speed durability deteriorates due to the heat storage. Further, when the band-shaped sound absorbing material is directly attached to the inner surface of the tire, there is a problem that the band-shaped sound absorbing material cannot follow the bending of the tire and breaks when the tire rolls.

On the other hand, when a notch is provided in the inner peripheral surface of the band-shaped sound absorbing material, it is possible to follow the deformation of the tire when the tire rolls, but the band-shaped sound absorbing material generated by the growth of the outer diameter of the tire when the tire is inflated. There is a problem that the tension in the circumferential direction cannot be sufficiently relaxed and the band-shaped sound absorbing material is easily peeled off.

Japanese Patent No. 4281874 Japanese Patent No. 5267288

An object of the present invention is to make a notch in the outer peripheral surface of the band-shaped sound absorbing material adhered to the inner surface of the tire, thereby following the growth of the outer diameter of the tire at the time of inflating the tire, relaxing the tension generated in the band-shaped sound absorbing material, and forming the band shape. It is an object of the present invention to provide a pneumatic tire capable of improving the durability of a sound absorbing material, promoting heat dissipation from the band-shaped sound absorbing material, and improving high-speed durability.

The pneumatic tire of the present invention for achieving the above object has a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and these sidewall portions. In a pneumatic tire having a pair of bead portions arranged inside in the tire radial direction and having a strip-shaped sound absorbing material adhered to the inner surface of the tread portion along the tire circumferential direction, a plurality of bead portions are provided on the outer peripheral surface of the strip-shaped sound absorbing material. has a notch on, and both ends of each cut is terminated inside of the band-shaped sound absorbing material, said incisions opening on the inner peripheral surface of the belt-shaped sound absorbing material on the one that opens to the outer peripheral surface of the belt-shaped sound absorbing material It is characterized by not doing so.

In the present invention, since a plurality of cuts are formed on the outer peripheral surface of the band-shaped sound absorbing material and at least one end of each cut is terminated inside the band-shaped sound absorbing material, the tire has an outer diameter when the tire is inflated. When it grows, the notch of the band-shaped sound absorbing material is opened to follow the deformation of the tire, relax the tension generated in the band-shaped sound absorbing material, and improve the adhesiveness between the band-shaped sound absorbing material and the inner surface of the tire. Thereby, the durability of the band-shaped sound absorbing material can be improved. In addition, since the notch of the band-shaped sound absorbing material is opened when the tire is inflated, the heat dissipation area of the band-shaped sound absorbing material is increased, so that heat dissipation from the band-shaped sound absorbing material can be promoted and the high-speed durability of the pneumatic tire can be improved. It will be possible. Further, since at least one end of each notch is terminated inside the band-shaped sound absorbing material, the movement of the band-shaped sound absorbing material can be restricted, and the rubbing between the band-shaped sound absorbing materials can be suppressed. ..

In the present invention, it is preferable that both ends of each notch are terminated inside the band-shaped sound absorbing material. This makes it possible to more effectively suppress the rubbing between the band-shaped sound absorbing materials.

In the present invention, the angle θ of the plurality of cuts with respect to the tire circumferential direction is preferably in the range of 40 ° ≦ θ ≦ 90 °. As a result, when the outer diameter of the tire grows when the tire is inflated, the notch of the band-shaped sound absorbing material is opened to follow the deformation of the tire, relax the tension generated in the band-shaped sound absorbing material, and connect the band-shaped sound absorbing material to the inner surface of the tire. It is possible to improve the adhesiveness. In addition, it is possible to promote heat dissipation from the band-shaped sound absorbing material and improve the high-speed durability of the pneumatic tire.

In the present invention, the depth of cut d is preferably 20% or more with respect to the thickness D of the band-shaped sound absorbing material. Further, the upper limit value is preferably 90% or less, more preferably 55% or less. As a result, when the outer diameter of the tire grows when the tire is inflated, the notch of the band-shaped sound absorbing material is opened, heat dissipation from the band-shaped sound absorbing material is promoted, and the high-speed durability of the pneumatic tire can be improved.

In the present invention, the cut width a of the band-shaped sound absorbing material is preferably 40% to 90% with respect to the width A of the band-shaped sound absorbing material. As a result, it follows the growth of the outer diameter of the tire when the tire is inflated, relaxes the tension generated in the band-shaped sound absorbing material, improves the durability of the band-shaped sound absorbing material, promotes heat dissipation from the band-shaped sound absorbing material, and promotes heat dissipation from the band-shaped sound absorbing material. Contributes to the improvement of high-speed durability.

In the present invention, the volume of the band-shaped sound absorbing material is preferably 10% to 30% with respect to the lumen volume of the tire. This makes it possible to further obtain the sound absorbing effect of the band-shaped sound absorbing material. By increasing the volume of the band-shaped sound absorbing material in this way, an excellent noise reduction effect can be obtained, and even a large band-shaped sound absorbing material can exhibit a good tension relaxation effect and a heat dissipation effect. The volume of the cavity is the volume of the cavity formed between the tire and the rim when the tire is rim-assembled on the regular rim and the regular internal pressure is applied. A "regular rim" is a rim defined for each tire in a standard system including a standard on which a tire is based. For example, a standard rim for JATTA, a "Design Rim" for TRA, or ETRTO. If so, it is set to "Measuring Rim". However, if the tire is a tire installed on a new car, the volume of the cavity will be calculated using the genuine wheel on which this tire is assembled. "Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. If it is JATTA, it is the maximum air pressure, and if it is TRA, it is the table "TIRE LOAD LIMITED AT VARIOUS". The maximum value described in "COLD INFLATION PRESSURES", and if it is ETRTO, it is "INFRATION PRESSURE", but if the tire is a new car tire, it is the air pressure displayed on the vehicle.

In the present invention, it is preferable that the band-shaped sound absorbing material has a missing portion at at least one position in the tire circumferential direction. This makes it possible to withstand the shear strain of the adhesive surface due to the expansion due to the inflation of the tire for a long time.

FIG. 1 is a perspective sectional view showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the equator showing a pneumatic tire according to the embodiment of the present invention. FIG. 3 is a developed view showing a part of the band-shaped sound absorbing material adhered to the inner surface of the pneumatic tire of the present invention on the adhesive surface side. FIG. 4 is a cross-sectional view of the sound absorbing material of FIG. 3 in the tire circumferential direction. 5 (a) to 5 (e) show a modification of the notch of the band-shaped sound absorbing material adhered to the inner surface of the pneumatic tire of the present invention, and FIGS. 5 (a) to 5 (e) show the adhesive surface side of each modification. It is a development view which shows a part of.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a pneumatic tire according to an embodiment of the present invention. In FIG. 1, the pneumatic tire of the present embodiment has a tread portion 1 extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and these sidewall portions. It is provided with a pair of bead portions 3 arranged inside the tire radial direction of the tire 2.

In the pneumatic tire, the band-shaped sound absorbing material 6 is adhered to the region corresponding to the tread portion 1 of the tire inner surface 4 via the adhesive layer 5 along the tire peripheral direction. The band-shaped sound absorbing material 6 is made of a porous material having open cells, and has a predetermined sound absorbing property based on the porous structure. Polyurethane foam may be used as the porous material of the band-shaped sound absorbing material 6. On the other hand, as the adhesive layer 5, a double-sided adhesive tape is preferable.

A plurality of notches 7 extending in the tire width direction are formed on the outer peripheral surface of the band-shaped sound absorbing material 6, that is, the adhesive surface with the tire. Further, both ends of each notch 7 are terminated inside the band-shaped sound absorbing material 6, and there is no communication with both ends of the band-shaped sound absorbing material 6 in the width direction. One end of each notch 7 may be terminated inside the band-shaped sound absorbing material 6, and only the other end of the notch 7 may communicate with the end of the band-shaped sound absorbing material 6 in the width direction.

In the pneumatic tire described above, a plurality of cuts 7 are formed on the outer peripheral surface of the strip-shaped sound absorbing material 6, and at least one end of each cut 7 is terminated in the strip-shaped sound absorbing material 6, so that the tire can be inserted. When the outer diameter of the tire grows during frying, the notch 7 of the band-shaped sound absorbing material 6 opens to follow the deformation of the tire, relax the tension generated in the band-shaped sound absorbing material 6, and bond the band-shaped sound absorbing material 6 to the tire inner surface 4. It is possible to improve the sex. In particular, when a large amount of bending occurs in the tire, breakage is likely to occur at the interface between the band-shaped sound absorbing material 6 and the adhesive layer 5, but by adding a notch 7 to the band-shaped sound absorbing material 6, such breaking is effective. Can be prevented. Thereby, the durability of the band-shaped sound absorbing material 6 can be improved. Further, since the notch 7 of the band-shaped sound absorbing material 6 is opened when the tire is inflated, the heat dissipation area of the band-shaped sound absorbing material 6 is increased, so that heat dissipation from the band-shaped sound absorbing material 6 is promoted and the high-speed durability of the pneumatic tire is improved. It is possible to improve. Further, since both ends of each notch 7 are terminated inside the band-shaped sound absorbing material 6, the movement of the band-shaped sound absorbing material 6 can be restricted, and the rubbing between the band-shaped sound absorbing materials 6 can be suppressed. ..

As shown in FIG. 3, the angle of the notch 7 with respect to the tire circumferential direction is defined as the angle θ. In FIG. 3, Tc is the tire circumferential direction and Tw is the tire width direction. At this time, the angle θ of the notch 7 with respect to the tire circumferential direction is in the range of 40 ° ≦ θ ≦ 90 °. By setting the angle θ appropriately in this way, the notch 7 of the band-shaped sound absorbing material 6 opens when the tire is inflated, follows the deformation of the tire, relaxes the tension generated in the band-shaped sound absorbing material 6, and the band-shaped sound absorbing material. It is possible to improve the adhesiveness between 6 and the inner surface 4 of the tire. Further, it is possible to promote heat dissipation from the band-shaped sound absorbing material 6 and improve the high-speed durability of the pneumatic tire. Here, if the angle θ is too small, it becomes difficult for the notch 7 to open when the tire is inflated, so that the above-mentioned tension relaxation effect and heat dissipation effect are reduced.

Further, in FIG. 3, the width of the notch 7 is defined as the width a, and the width of the band-shaped sound absorbing material 6 is defined as the width A. At this time, the width a of the notch 7 of the band-shaped sound absorbing material 6 is 40% to 90% with respect to the width A of the band-shaped sound absorbing material 6. In particular, it is more preferable that the width a of the notch 7 of the band-shaped sound absorbing material 6 is 50% to 80% with respect to the width A of the band-shaped sound absorbing material 6. By setting the width a to an appropriate size with respect to the width A in this way, the outer diameter growth of the tire at the time of inflating the tire is followed, the tension generated in the band-shaped sound absorbing material 6 is relaxed, and the band-shaped sound absorbing material is relaxed. In addition to improving the durability of 6, it promotes heat dissipation from the band-shaped sound absorbing material 6 and contributes to the improvement of high-speed durability of the tire. Here, if the width a of the notch 7 is too wide, the band-shaped sound absorbing material 6 becomes difficult to stabilize, and the effect of improving the durability of the band-shaped sound absorbing material 6 decreases.

FIG. 4 is a cross-sectional view of the strip-shaped sound absorbing material 6 in the tire circumferential direction. The notch 7 is open only on the outer peripheral surface (adhesive surface with the tire) of the band-shaped sound absorbing material 6, and is not opened on the inner peripheral surface of the band-shaped sound absorbing material 6. The depth of the notch 7 is defined as the depth d, and the thickness of the band-shaped sound absorbing material 6 is defined as the thickness D. At this time, the depth d of the notch 7 is 20% or more with respect to the thickness D of the band-shaped sound absorbing material 6, and the upper limit thereof is preferably 90% or less, more preferably 55% or less. By setting the depth d to an appropriate size with respect to the thickness D in this way, the notch 7 of the band-shaped sound absorbing material 6 opens when the tire is inflated, and heat dissipation from the band-shaped sound absorbing material 6 can be promoted. It will be possible. Here, if the depth d of the notch 7 is too shallow, heat dissipation from the band-shaped sound absorbing material 6 becomes dull, and the high-speed durability of the tire deteriorates.

In the above-mentioned pneumatic tire, the volume of the band-shaped sound absorbing material 6 is 10% to 30% with respect to the lumen volume of the tire. The width of the band-shaped sound absorbing material 6 is 30% to 90% of the tire contact width. By appropriately setting the volume and width of the band-shaped sound absorbing material 6 in this way, it is possible to further obtain the sound absorbing effect of the band-shaped sound absorbing material 6. Here, if the volume of the band-shaped sound absorbing material 6 is less than 10% with respect to the lumen volume of the tire, the sound absorbing effect cannot be appropriately obtained. Further, when the volume of the band-shaped sound absorbing material 6 exceeds 30% with respect to the lumen volume of the tire, the noise reduction effect due to the cavity resonance phenomenon becomes constant, and further reduction effect cannot be expected.

Further, as shown in FIG. 2, the band-shaped sound absorbing material 6 has a missing portion 9 at one position in the tire circumferential direction. The missing portion 9 is a portion on the tire circumference where the band-shaped sound absorbing material 6 does not exist. By providing the missing portion 9 in the band-shaped sound absorbing material 6, it is possible to withstand the shear strain of the adhesive surface caused by the expansion due to the inflating of the tire for a long time, and the shear strain generated in the adhesive surface of the band-shaped sound absorbing material 6 can be effectively applied. It can be relaxed. It is preferable to provide such a missing portion 9 at one location or three to five locations on the tire circumference. That is, if the missing portions 9 are provided at two locations on the tire circumference, the deterioration of tire uniformity becomes remarkable due to the mass imbalance, and if the missing portions 9 are provided at six or more locations on the tire circumference, the manufacturing cost increases. It becomes noticeable.

If the missing portions 9 are provided at two or more locations on the tire circumference, the band-shaped sound absorbing material 6 is interrupted in the tire circumference direction. Even in such a case, for example, an adhesive layer made of double-sided adhesive tape. If a plurality of strip-shaped sound absorbing materials 6 are connected to each other with another laminate such as 5, these strip-shaped sound absorbing materials 6 can be handled as an integral member, so that the work of attaching to the tire inner surface 4 can be performed. It can be done easily.

As the cuts 7, in addition to those shown in FIG. 1, when the cuts 7 are arranged alternately as shown in FIG. 5 (a), or as shown in FIG. 5 (b), the cuts 7 are moved to one side of the band-shaped sound absorbing material 6. When arranged in a random manner, as shown in FIG. 5 (c), a case of randomly arranging can be illustrated. Further, when the notches 7 are arranged diagonally in a staggered manner as shown in FIG. 5 (d), a case where the notches 7 in two directions are arranged so as to intersect each other as shown in FIG. 5 (e) can be exemplified. ..

Hereinafter, the present invention will be further described with reference to Examples, but the scope of the present invention is not limited to these Examples.

With a tire size of 275 / 34ZR20, a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and these sidewall portions are arranged inside the tire radial direction. In a pneumatic tire provided with a pair of bead portions and a band-shaped sound absorbing material adhered to the inner surface of the tread portion along the tire circumferential direction, the presence or absence of a notch, the arrangement of the notch, the notch angle θ, and the notch depth (depth). Treads d / thickness D × 100%) and cut width (width a / width A × 100%) are set as shown in Tables 1 and 2, and tires of Conventional Examples, Comparative Examples and Examples 1 to 12 are manufactured. bottom.

For these test tires, the durability of the band-shaped sound absorbing material at high speed and high bending was evaluated by the following test method, and the results are shown in Tables 1 and 2.

In Tables 1 and 2, the arrangement of the cuts is defined as "communication" when the cuts formed on the outer peripheral surface of the band-shaped sound absorbing material communicate with both ends in the width direction of the band-shaped sound absorbing material. If there is no communication at both ends in the width direction, it is considered as "non-communication".

High speed durability:
Each test tire was assembled on a wheel having a rim size of 20 × 9 1/2 J, and a running test was carried out with a drum tester under the conditions of an air pressure of 360 kPa and a load of 5 kN. Specifically, the initial speed was set to 250 km / h, the speed was increased by 10 km / h every 20 minutes, the tire was run until a failure occurred, and the arrival step (speed) was measured. The results are shown in Tables 1 and 2.

Durability of strip-shaped sound absorbing material during high deflection:
Durability referred to here mainly indicates an evaluation against rubbing between band-shaped sound absorbing materials. After assembling each test tire to a wheel with a rim size of 20 x 9 1/2 J and conducting a running test with a drum tester under the conditions of a running speed of 80 km / h, an air pressure of 160 kPa, a load of 8.5 kN, and a mileage of 6,000 km. , The presence or absence of rubbing between the band-shaped sound absorbing materials was visually confirmed. The results are shown in Tables 1 and 2. In the above items, the case where there is no rubbing between the band-shaped sound absorbing materials is indicated by "◎", the case where the rubbing between the band-shaped sound absorbing materials is less than 1/8 of the entire band-shaped sound absorbing materials is indicated by "○", and the cases where the band-shaped sound absorbing materials are not rubbed against each other are indicated by "○". The case where the rubbing between the band-shaped sound absorbing materials is 1/8 or more and less than 1/4 of the whole band-shaped sound absorbing material is indicated by "Δ", and the case where the rubbing between the band-shaped sound absorbing materials is 1/4 or more of the entire band-shaped sound absorbing material is indicated by "x". ..

As can be seen from Tables 1 and 2, the pneumatic tires of Examples 1 to 12 were simultaneously improved in high-speed durability and durability of the band-shaped sound absorbing material at the time of high bending.

On the other hand, in the comparative example, since the cuts were formed so as to communicate with both ends of the band-shaped sound absorbing material in the width direction, the effect of improving the durability of the band-shaped sound absorbing material at the time of high bending was not sufficient.

1 Tread part 2 sidewall part 3 bead part 4 tire inner surface 5 adhesive layer 6 band-shaped sound absorbing material 7 notch 8 hollow part 9 missing part

Claims (6)

A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged inside the tire radial direction of these sidewall portions. includes a pneumatic tire band sound absorbing material is adhered along the tire circumferential direction on the inner surface of the tread portion, a plurality of notches in an outer circumferential surface of the belt-shaped sound absorbing material, and the both ends of each cut the A pneumatic tire that is terminated inside the tread-shaped sound absorbing material, and the notch opens on the outer peripheral surface of the tread-shaped sound absorbing material, but does not open on the inner peripheral surface of the tread-shaped sound absorbing material. The pneumatic tire according to claim 1, wherein the angle θ of the notch with respect to the tire circumferential direction is in the range of 40 ° ≤ θ ≤ 90 °. The pneumatic tire according to claim 1 or 2 , wherein the depth of cut d is 20% or more with respect to the thickness D of the strip-shaped sound absorbing material. The pneumatic tire according to any one of claims 1 to 3 , wherein the cut width a of the band-shaped sound absorbing material is 40% to 90% with respect to the width A of the band-shaped sound absorbing material. The pneumatic tire according to any one of claims 1 to 4 , wherein the volume of the band-shaped sound absorbing material is 10% to 30% with respect to the lumen volume of the tire. The pneumatic tire according to any one of claims 1 to 5 , wherein the band-shaped sound absorbing material has a missing portion at at least one position in the tire circumferential direction.

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